Military aircraft and vehicles such as tanks and ships typically have access panels that are attached with fasteners. Nuts may be permanently affixed to interior panels, for example, to receive the threaded shaft of the fasteners. In many military applications, detection of the vehicle by radar is undesirable, and an effort has been made to design aircraft, ships and land vehicles, with substantially smooth exterior contours which may be coated with special films to reduce radar signatures and thus inhibit detection.
A problem with stealth aircraft and vehicles is that the presence of screws and other fasteners on the exterior surface contributes to the radar signature. Typically a recessed screw head is used to install doors and panels. This involves countersinking the hole in the surface the screw enters and using a chamfered screw head to fit within the countersunk hole so that the head of the screw is flush with the surface. However, even the use of recessed screws is detectable in the signature of the vehicle.
The recessed exterior screws and fasteners on stealth aircraft and vehicles must be covered to reduce the radar signature. Special coatings are typically used to decrease radar detection of a vehicle. When applied to the fasteners, the coatings fill in the driving engagement mechanisms, and thus the fasteners are not easily accessible by service personnel when needed for repair or maintenance. The head and recess of the fastener must then be scraped to remove the debris, which is time-consuming.
One prior art method involves using an aero-smoothing caulk to cover the heads of fasteners to decrease radar detection. The aero-smoothing caulk must be removed prior to accessing the fastener, and then must be reinstalled following maintenance. This is disadvantageous because the caulk or putty is difficult and time-consuming to remove. Another prior art solution involves bonding donut-shaped plastic attachments on the surface of the fastener heads. This method creates an expensive fastener that is easily damaged and must therefore be replaced frequently.
What is needed is a fastening device for stealth aircraft, vehicles and weapons absent these problems of the prior art.